1. Field of the Invention
This invention relates to mold forming machines and more particularly to mold forming machines and conversion units for converting a mold forming machine from a dry mold material forming process to a moist mold material forming process by which mold items may be formed from a curable mold material.
2. Description of the Prior Art
The prior art has known various types of dry mold material mold forming machines and moist material mold forming machines for forming a mold item or a core item in a foundry process. The term mold item is used herein to include both molds and cores as conventionally used in the trade. In the dry mold material mold forming processes a moldbox having a mold cavity was heated by gas flame or electric heating. A dry mold material with a thermosetting binder was injected into the mold cavity to form the mold item. This hot mold forming process could be used to form a shell mold or core whereas the moist mold material mold forming process was generally restricted to form a solid mold or core. The dry mold material was generally easier to use than the moist mold material since the thermosetting binder on the dry mold material did not become sticky until reaching an elevated temperature.
The moist mold material mold forming processes generally used a gas or heat curable mold material having a sticky gas or heat curable binder and a sand type of material making this combination more difficult to work with than the thermosetting mold material. After the gas curable mold material was injected into the moldbox cavity, a catalytic gas was introduced into the mold cavity for several seconds and then purged from the mold cavity so that the mold item could be removed from the moldbox.
In the past many hot mold forming processes were used to manufacture various types of mold and core item. However, since the cost of energy and natural gas has substantially increased in the past several years, many of the hot mold forming processes are now more expensive than comparable cold mold forming processes. Many machines are now in use in foundries all over the world which were specifically designed for a hot mold forming process.
Therefore, it is an object of this invention to provide a conversion unit for converting a mold forming machine from a dry mold material mold forming process to a moist mold material mold forming process which unit can be easily adapted to the many existing hot mold forming machines.
Another object of this invention is to provide a conversion unit for converting a mold forming machine from a dry mold material mold forming process to a moist mold material mold forming process incorporating aperture sealing means which is rotatably mounted relative to a mold material injection means for sealing an aperture in the moldbox prior to introduction of a curing gas.
Another object of this invention is to provide a conversion unit for converting a mold forming machine from a dry mold material mold forming process to a moist mold material mold forming process having adjustable conversion unit support means for adjustably mounting the mold material injection means relative to the mold forming machine in accordance with the size of the moldbox of the mold forming machine.
Another object of this invention is to provide a conversion unit for converting a mold forming machine from a dry mold material mold forming process to a moist mold material mold forming process including first means for linearly advancing the mold material injection means adjacent the moldbox of the mold forming machine to enable injection of the mold material into aperture means of the moldbox and for retracting the mold material injection means from the moldbox after injection of the mold material enabling second movement means to rotate aperture sealing means adjacent the aperture means of the moldbox to be linearly advanced by the first movement means to seal the aperture means of the moldbox.
Another object of this invention is to provide a conversion unit for converting a mold forming machine from a dry mold material mold forming process to a moist mold material mold forming process including control means and mold material curing means including gas injection means for injecting a curing gas within the mold cavity upon sealing of the mold cavity.
Another object of this invention is to provide a conversion unit for converting a mold forming machine from a dry mold material mold forming process to a moist mold material mold forming process by which the mold making process may be performed at a substantial saving of energy.